Telescoping mast assembly

ABSTRACT

A telescoping mast assembly includes a plurality of interconnected mast sections nested within each other for movement between a fully retracted height and a fully extended height. A novel, rigid drive assembly, disposed within the interconnected mast sections, telescopes the mast sections to any position between the fully retracted and the fully extended heights. The rigid drive assembly is constructed of two interconnected, flexible chain elements which accurately position the interconnected mast sections.

This application is a continuation of application Ser. No. 579,944,filed on Sept. 10, 1990, now abandoned.

The present invention relates to the art of telescoping masts and moreparticularly to a telescoping mast having a rigid drive assembly fortelescoping mast sections to any position between fully retracted andfully extended heights.

The present invention is particularly applicable for use in quickerecting telescoping masts and will be particularly described withparticular reference thereto; however, the invention has much broaderapplications and may be used in various other applications for movingrelatively heavy loads in a generally straight line.

BACKGROUND OF THE INVENTION

Quick erecting telescoping masts are used for many applicationsincluding civilian, industrial and military applications throughout theworld. Quick erecting telescoping masts are particularly suited forapplications wherever there is a need for portable masts requiring fastsetup and teardowns with minimum power and effort. In addition tonumerous military applications, including target acquisitions,surveillance and field communications, quick erecting telescoping mastsare utilized commercially to support a wide variety of antennas,elevated testing equipment, floodlights and cameras. Free-standing mastscan be installed on a wide variety of vehicles and shelters.

In the past, the telescoping masts were typically pneumaticallyoperated. This entailed airtight seals between the adjacent mastsections so that the air which was delivered into the bottom of the mastwould not bleed out of the system and cause the mast to retract.

Another problem which could affect the usefulness of the pneumaticallyoperated masts was their being damaged during operation. For instance,if a hole was formed in a section of a mast by a projectile, the aircould bleed out and the mast could collapse. Moreover, sometimes theprojectile could forma hole with a ragged edge which prevented thetelescoping mast from retracting.

A related problem associated with pneumatically operated masts relatedto ice formed between the mast sections and preventing the telescopingmast from being extended or retracted.

A further deficiency of the pneumatically operated telescoping masts wasthat they primarily had two positions. Either they were fully retractedor fully extended. However, to partially extend the telescoping mast wastypically beyond the capabilities of the portable, pneumaticallyoperating mast equipment. Since an antenna which incorporates the mastitself can have its frequency affected by the height of the mast, theability to partially extend the mast to a desired height is an importantfeature which was not easily accomplished in the prior art. Further,even when a pneumatically operated telescoping mast was partiallyextended, the precise position of the upper end was not known. Thus, itwas difficult to ascertain the exact frequency of the mast and antennaassembly when the antenna was in fully extended position.

INVENTION

The present invention is specifically directed to a telescoping mastassembly incorporating a plurality of interconnected mast sectionsnesting within each other and adopted for movement between a fullyretracted height and a fully extended height. A rigid drive assemblytelescopes the mast sections to any position between the fully retractedand the fully extended height. The rigid drive assembly is constructedof at least two flexible drive elements which accurately position theinterconnected mast sections.

It is believed that the prior art does disclose a plurality of separatestrips of material being fed together and wrapped with a separate wireto form a rigid structure. However, this can be distinguished from thepresent invention where the flexible chains have the latching mechanism,for interconnecting the chains and forming the rigid drive, as anintegral part of the chain elements.

In accordance with the invention, one of the flexible drive elements isa driven chain constructed of a plurality of interconnected driven chainlinks. The driven chain has a first driven section extending in thelongitudinal direction and connected to the interconnected mastsections. The driven chain is connected to a second flexible driveelement which comprises a drive chain with a first drive sectionextending in the longitudinal direction of and connected to theinterconnected mast sections.

Another important aspect of the present invention relates to a latchingmechanism interconnecting the first drive section and the first drivensection to construct the rigid drive assembly. It will be appreciatedthat the first driving section and the first driven section are disposedadjacent to each other and latched together to form the rigid driveassembly which operates the interconnected mast sections.

Turning to the specifics of the latch assembly, the drive chain isconstructed of a plurality of interconnected drive chain links whereinadjacent drive chain links are interconnected by a drive link pin. Thedrive chain links have latch elements which are connected to the drivenchain links. The driven chain is also constructed of a plurality ofinterconnected driven chain links wherein the adjacent driven chainlinks are interconnected by a driven link pin. The driven links havelatch elements affixed thereto for connecting the driven links to thedrive links so that the first driven section is driven by the movementof the first drive section.

Turning to the details of the drive links, each has a plate elementaffixed thereto and disposed with respect to each other in the firstdrive section to abut one another and rigidly affix adjacent drive linksto each other. One type of plate element is constructed of asubstantially rectangular plate having a substantially flat upper edgesurface with a plate slot formed therein and an opposing substantiallyflat lower edge surface. A second type of plate element is constructedof a substantially rectangular plate having substantially flat upper andlower edge surfaces. The first and second types of plate elements arealternately disposed between each other in the first drive sectionwhereby the flat upper edge surface of the second plate element abutsthe substantially flat lower edge surface of the first plate element andthe substantially flat upper edge surface of the first plate elementabuts the substantially flat lower edge surface of the second plateelement with the plate slot therebetween.

Turning now to the specifics of the driven links, each has a projectingelement attached thereto for interconnecting the driven links to thedrive links in the first drive section. There are two types ofprojecting elements. A first type of projecting element is constructedof a rod having a substantially flat first end with a rectangular crosssection. Each of the first type of projecting elements is affixed at asecond end, oppositely disposed from said first end, to extend outwardlyfrom the longitudinally disposed first driven section. The second typeof projecting element is constructed of a rod having a substantiallyrectangular cross section with a substantially flat upper surface and asubstantially flat lower surface. The flat lower surface has aprojecting element slot formed therein. The first and second projectingelements are affixed to alternate, adjacent driven links whereby thesubstantially flat ends of the first projecting elements abut against afirst plate surface of the first plate elements to maintain a distancebetween the drive and driven sections. The second projecting element isreceived within the plate slot so that the projecting element slotinterconnects with the plate slot formed in the upper edge of the firstplate. The projecting elements can be flexibly mounted to the drivenlinks to prevent jam-ups due to misalignment of the projecting elementsand the plate elements.

Another aspect of the present invention relates to the space savingadvantages. Specifically, a second drive section of the drive chain isconnected at a first end to the first drive section and extendstransversely to the second drive section. A drive chain spool isconnected to a second end of the second drive section for winding thedrive chain thereon. As with the drive chain, the driven chain alsoincludes a second driven section connected at a first end to the firstdriven section and extending transversely to the first driven section.Further, a driven chain spool is connected to a second end of the seconddriven section for winding the driven chain thereon. It can beappreciated, that the use of a drive chain spool and a driven chainspool can significantly reduce the space required to support the driveassembly associated with the telescoping mast assembly of the presentinvention.

In order to operate the drive chain, a drive sprocket is disposed at theintersection of the first and second drive sections for engaging thedrive links to extend and retract the drive section. The drive sprocketis operated by conventional means such as a motor and gear reductionunit.

Further, in accordance with the invention, the drive sprocket ispreferably constructed with a substantially cylindrical peripheralsurface including a plurality of sprocket grooves having substantiallyequal spacing about the peripheral surface for engaging the chain driverollers. The cylindrical peripheral surface also functions to press theplate elements into abutment with each other to rigidly affix adjacentdrive links. The cylindrical peripheral surface also presses the plateelements towards the drive chain. The effect of the drive sprocketoperation is a tendency to move the drive chain towards the driven chainand possibly diminish the rigidity of the chain.

Therefore, the present invention further includes a biasing device forpressing the plate elements towards the drive sprocket whereby a rigidinterconnection between the drive plates in the first drive sections ismaintained. The biasing device includes first and second cylindricalrollers spaced apart to receive the first driven section of theinterconnected driven links. The cylindrical rollers are connected by ashaft. Springs are attached to the shaft to bias the cylindrical rollerstowards the drive sprocket. The biasing device also presses the drivenchain towards the drive chain to maintain the interconnection betweenthe two chains.

Also in accordance with the invention, the position of the mast can bedetermined by viewing indicia provided on either the drive or drivenchain to indicate the precise extended position of the mast.

Another aspect of the present invention relates to the connectionbetween the first driven section, the first drive section and theinnermost, movable mast section. This connection can include a balljoint in cooperative relationship with the innermost movable mast toaccommodate any misalignment between the rigid drive assembly and thetelescoping mast.

Still another aspect of the present invention is that wiring can beprovided internal to the mast assembly.

A yet further aspect of the present invention is that the chain can bemanufactured from ferrous, non-ferrous, metallic and non-metallicmaterials.

The primary object of the present invention is to provide a telescopingmast assembly including a plurality of interconnected mast sectionsnested within each other for movement between a fully retracted heightand a fully extended height. The telescoping mast assembly explainedhereinbefore includes a novel rigid drive assembly for telescoping themast sections to any position between a fully retracted and fullyextended heights. A further object is the provision of this novel driveassembly.

Another object of the present invention is to provide a telescoping mastassembly where the rigid drive assembly is constructed of two flexibledrive elements which can be easily stored in a relatively small space.

A further object of the present invention is to provide a telescopingmast assembly which provides accurate positioning of the mast.

A still further object of the present invention is to provide atelescoping mast assembly which is relatively rugged while beingrelatively easy to maintain.

Yet another object of the present invention is to provide a telescopingmast assembly which obviates the problems and limitations of the priorart devices.

These and other objects and advantages will become apparent from thefollowing description taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing a telescoping mast assembly incorporatinga rigid drive assembly for telescoping the mast sections to any positionbetween the fully retracted and the fully extended heights;

FIG. 2 is a side view of a telescoping mast assembly incorporated into atruck for supporting equipment in accordance with the preferredembodiment of the present invention;

FIG. 3 is a perspective view of the first drive section and the firstdriven section in their rigid, latched condition;

FIG. 4 is a side view of the first drive section latched to the firstdriven section.

FIG. 5 is a view through section 5--5 of FIG. 4;

FIG. 6 is a view through section 6--6 of FIG. 4;

FIG. 7 is a view through section 7--7 of FIG. 4;

FIG. 8 is a side view showing the interconnection between the drivesprocket and the first and second drive sections and the operation ofthe biasing component for pressing both the driven chain and the drivenchain towards the drive sprocket;

FIG. 9 is a view through section 9--9 of FIG. 8;

FIG. 10 is a view through section 10--10 of FIG. 9;

FIG. 11 is a side view illustrating the rigid drive assembly extendinglongitudinally upwards through telescoping mast sections;

FIG. 12 is a view through 12--12 of FIG. 11;

FIG. 13 is a side view illustrating the interconnection between therigid drive assembly and the innermost mast section;

FIG. 14 is a view of a second embodiment of both the first drive sectionand first driven section in the interconnected latched condition;

FIG. 15 is a view through section 15--15 of FIG. 14; adjacent drivelinks of the drive chain;

FIG. 17 is a view through 17--17 of FIG. 14;

FIG. 18 is a view through 18--18 of FIG. 14;

FIG. 19 is a view of a third embodiment of the first drive section andthe first drive section being connected by a latching structure; and,

FIG. 20 is a view through 20--20 of FIG. 19.

PREFERRED EMBODIMENT

Referring now to the drawings wherein the showings are for the purposeof illustrating preferred embodiments of the invention only, and not forthe purpose of limiting same, FIG. 1 shows a telescoping mast assembly10 for use with a vehicle, such as truck 11, as shown in FIG. 2. Thetelescoping mast assembly 10 includes a plurality of interconnected mastsections 12-16 as generally shown in FIG. 1. Although six interconnectedmast sections are illustrated, it is within the terms of the presentinvention to incorporate any number as desired. Typically, the mastextends in a range from about 20 feet to about 150 feet. However, it iswithin the terms of the invention to lengthen or shorten the range asrequired. As illustrated in FIG. 1, the outermost mast section 12 isstationary and is immovably affixed to a movable support structure suchas vehicle 11. The innermost mast section 16 is attached to any desiredoperating equipment 18, such as an antenna, which is supported by themast assembly 10.

As further illustrated in FIG. 1, each of the interconnected mastsections 14 through 16 are cylindrical tubes having outwardly extendingcylindrical flanges 20 and 22 which have a slightly smaller diameterthan the internal diameter of the tubes 12 and 14, respectively in alongitudinal direction. This enables the tubes to telescope in and outof adjacent tubes. The cylindrical flanges are important because theyalso provide a bearing surface between the cylindrical tubes. Referringto FIG. 11, a seal 24 can be provided in a groove 26 formed in thecylindrical flange 20 to seal the interior cavity 28 of the tube 12. Inaddition, each of the tubes includes an inwardly extending cylindricalflange 30 having a seal 32 disposed in a groove 34. The conventionalseal 32 generally acts against the external cylindrical surface of theadjacent nested mast sections 14, 14', 14", 14''' and 16 to preventundesirable elements, such as condensation, from collecting betweenadjacent tubes. Structural elements indicated by primed, double primedand triple primed reference numerals, throughout the instantspecification, are substantially identical to the element designated bythe unprimed reference numeral. It is, however, within the terms of thepresent invention to provide any type of seal structure or delete theseal structure if desired.

Typically, the individual mast sections are manufactured from highstrength, heat treated annodized aluminum alloy tubes and collars. It isalso within the terms of the present invention to form the tubes ofother materials such as carbon fiber sheets which are advantageousbecause of their light weight relative to their high strength. Moreover,these materials can easily be shaped into cross-sections, other thancircular, as desired.

The bottom most mast section 12 is typically received within a flange 36which can rotatably receive the mast 12 in any conventional manner. Ifdesired, a handle 37, as illustrated in FIG. 2, can be attached to themast 12 in order to rotate the telescoping mast assembly 10 to anydesired position.

The present invention is particularly directed to a rigid drive assembly38 for telescoping the mast sections 14 and 16 to any position between afully retracted height, not illustrated, and a fully extended height asshown in FIG. 2. The rigid drive assembly 38 is constructed of at leasttwo flexible drive components or elements 40 and 42 to accuratelyposition the interconnected mast sections 10. Flexible drive element 42includes a driven chain 44 constructed of a plurality of interconnecteddriven chain links 46. The chain links 46, as illustrated in FIG. 4, arepreferably constructed of a roller chain assembly. An inside drivenchain link 48 consists of two inside driven plates 50 and 52 and twodriven rollers 54 and 56 carried by bushings, not illustrated, disposedbetween the inside or inner plates 50 and 52. Adjacent inside chainlinks 48 are connected to each other with outside or outer drivenpinlink plates 58 and 60 assembled with pins 62 and 64. The pins 62 and64 are received within the bushings supporting rollers 54 and 56. Theends of the pins 62 and 64 can be attached to the outer plates 58 and 60in any desired manner.

As seen in FIGS. 3 through 5, the driven chain 44 of driven element 42is disposed adjacent to the drive chain 66 of the drive element 40. Thespaced relationship between the drive element 40 and the driven element42 enables the latching mechanism 68 to interconnect driven chain 44 todrive chain 66. The interconnection occurs between the first drivesection 70 and the first driven section 72 to construct the rigid driveassembly 38. The first drive section 70 and the first driven section 72are disposed adjacent each other, as seen in FIG. 1. The first drivesection 70 extends from a drive sprocket 74 to a connector link 76.Similarly, the first driven section 72 extends from a chain translationelement 77 to the connector link 76.

Referring again to the construction details of latching mechanism 68,each of the driven chain links 46 has projecting element means 80attached thereto for interconnecting the driven chain links 46 to thedrive chain links 66 in the first drive section 70. The projectingelement means 80 comprises a plurality of first projecting elements 82preferably constructed of a rod having a substantially flat, first end84 with a substantially rectangular cross-section. The first projectingelements 82 are affixed at a second end 86 to inside plates 52 of thechain link 46. The first projecting elements 82 extend transverselyoutwardly from the longitudinally disposed first driven section 72. Theconnection of the first projecting element 82 to the inside plate 52 canbe done by any means such as a welded joint 88. It is however within thescope of the present invention to affix the projecting element 82 by anyother desired means such as forming it as an integral component of theinside plate 52.

The projecting element means 80 also comprises a plurality of secondprojecting elements 90 which are constructed of a rod having asubstantially rectangular cross section with a substantially flat uppersurface 92 and a substantially flat lower surface 94. The flat lowersurface 94 has a projecting element slot 96 formed therein. The secondprojecting elements 90 are affixed to an outside plate 60 by any meanssuch as weld joint 98.

Although both of the projecting elements 82 and 90 are securely affixedto the chain links 46, it is preferable that they are sized, i.e. have anarrow width, to be flexible with respect to the chain links in orderthat they can move to accommodate slight misalignment between the drivenchain 44 and the drive chain 66. Further, although the first projectingelements 82 are illustrated as being attached to the inside plates 52and the second projecting elements 90 are illustrated as being attachedto the outside plates 60, it is within the terms of the presentinvention to reverse the connections so that the first projectingelements 82 are affixed to the outside plates 60 and the secondprojecting elements 90 are attached to the inside plates 52. The detailsof the latching mechanism between the projecting element means 80 andthe drive chain 66 will be described hereinafter.

Turning our attention to the drive chain 66, it is constructed ofessentially the same elements as the driven chain 44. That is, there areinside plates 100 and 102 and rollers 104 and 106 which are disposed onbushings (not shown) between the inside plates 100 and 102. Outsideplates 108 and 110 are provided to connect adjacent links with pins 112and 114 which extend through the rollers 104 and 106 to connect adjacentdrive links together.

The drive chain 66 includes latching structure 68 comprising plateelement means 116. The plate element means includes a plurality of firstplate elements 118 constructed of substantially rectangular plates eachhaving a substantially flat upper edge surface 120 with a plate slot 122formed therein and an opposing substantially flat lower edge surface124. A plurality of second plate elements 126 are also constructed ofsubstantially rectangular plates each having substantially flat upperand lower edge surfaces 128 and 130, respectively.

The first plate elements 118 are affixed to the inside plates 108 and110 by any desired means such as joint welds 132. The first and secondplate elements 118 and 126, respectively, are alternately disposedbetween each other along the entire length of the drive chain 66.However, in the first drive section 70, the plate elements are disposedso that the flat upper edge surface 128 of the second plate element 126abuts against the substantially flat lower edge surface 124 of the firstplate element 118 and the substantially flat upper edge surface 120 ofthe first plate element having plate slot 122 abuts against thesubstantially flat lower edge surface 130 of the second plate element126 to provide an aperture 133 therebetween. The abutment of the plateelements 118 and 126 within the first drive section 70 causes theotherwise flexible drive chain 66 to form a rigid chain throughout thelength that the first and second plate elements abut one another.

To more fully understand the latching structure 68, an explanation ofthe interrelationship between the projection element means 80 and theplate element means 116 follows. The latching mechanism 68 interconnectsthe first drive section 70 and the first driven section 72 to constructthe rigid drive mechanism 38. Note that the first drive section isdisposed adjacent to the first driven section, as illustrated in FIG. 4.However, the drive chain 66 and the driven chain 44 are oriented at anapproximate 90 degree angle with respect to each other. In other words,the pins 62 and 64 of the driven chain link 48 are disposed atsubstantially a 90 degree angle with respect to the pins 112 and 114 ofthe drive chain 66. As seen in FIG. 4, the first projecting elements 82abut against first plate elements 118. Moreover, the second projectingelements 90 are received in the apertures 133 between the first andsecond plate elements 118 and 126 so that the projecting slot 96 engagesthe slot 122 and the upper surface abuts against the lower edge surface130 of the second plate element 126. At the same time, the projectingelements 90 are essentially locked into aperture 133. The firstprojecting elements 82 abut against the plate elements 118 to maintain aconstant distance between the drive chain and driven chain and toincrease the rigidity of the drive mechanism 38.

Referring to FIGS. 1 and 8, there is illustrated a second drive section134 connected at a first end 136 by a transition drive section 137, tothe first drive section 70. The second drive section 134 extendstransversely to the first drive section and is connected at a second end138 to a drive chain spool 140. The drive chain spool 140 can be of anyconventional design. It can be appreciated, that the use of a drivespool enables a long length of chain to be compactly stored in arelatively small space which is particularly advantageous in portableapplications such as in a vehicle 11 as shown in FIG. 2.

A drive sprocket 74, as shown in FIGS. 1, 8 and 9, is disposed at theintersection of first and second end transition drive sections 70 and134 and respectively, for engaging the drive chain 66 to extend andretract the first drive section 70 in the longitudinal direction so asto move the drive assembly as illustrated by arrow 148. For example, thelongitudinal movement of the drive assembly will effect the telescopingof the mast sections to any desired position between the fully retractedand fully extended heights. The drive sprocket 74 has a substantiallycylindrical peripheral surface 142 and includes a plurality of sprocketgrooves 144 having substantially equal spacing about the peripheralsurface 142 for engaging drive rollers 104 and 106 as the drive sprocketturns in the clockwise or counter-clockwise direction as illustrated byarrow 146. In FIG. 8, clockwise movement of sprocket 74 causes the chainto be moved upward in the longitudinal direction causing the mastsections to extend upwards. Conversely, turning the drive sprocket inthe counter-clockwise direction causes the drive chain 66 to movedownward and rolls the chain onto the spool 140. The rotation of thedrive sprocket 74 can be controlled by a motor 150 which operatesthrough a reducing gear mechanism 152 to rotate a shaft 154 andultimately the drive sprocket 74. The rotation of the drive sprocket canbe provided by any other conventional means and, if desired, can even bemanually operated.

In the operation of the drive sprocket 74, its cylindrical peripheralsurface 142 presses against the second plate surfaces, 156 and 158 offirst and second plate elements 118 and 126, respectively, to which thedrive chain 66 is attached. As shown in FIGS. 8 and 9, the peripheralsurface 142 abuts against an adjacent, overlying plate element andpresses it to rigidly affix it to an adjacent drive link. Concurrently,the cylindrical peripheral surface 142 also presses the second flatsurfaces 156 and 158 toward the drive section 72 in a transversedirection to the longitudinal direction of the first drive section 70.This results in a tendency for bowing the drive chain 66 in the drivesection 72 which reduces the rigidity of the rigid drive device 38. Toensure a high degree of rigidity, a bias means 160 is provided to pressagainst the first plate surfaces 162 and 164 of the plate elements 118and 126, respectively, and bias the plate elements towards the drivesprocket 74 to ensure a rigid interconnection between the drive platesin the first drive section.

Referring again to FIG. 8, as the sprocket 74 rotates to move the linksfrom the second drive section 134 into the first drive section 70, thereis also a tendency for the cylindrical peripheral surface 142 to movethe driven chain 44 in the driven section 70 transverse to thelongitudinal direction 148 which is to be maintained to ensure a rigidinterconnection via latching mechanism 38. To counteract this tendency,the bias means 160 provides a counter bias force in the direction of thedrive sprocket 74 to maintain a substantially parallel alignment of thedrive chain 66 and the driven chain 44 throughout the first drive anddriven sections 72 and 70.

The biasing means 160 can include first and second cylindrical rollers166 and 168 spaced apart from each other to receive the first drivechain section 70 of interconnected driven links 48. The cylindricalrollers 166 and 168 are connected to each other by a shaft 170. Asupport block 172 is disposed between the cylindrical rollers andaffixed thereto by the shaft 170. A first side 174 of the support block172 is disposed in the longitudinal direction of the first drivensection 72 and includes a groove 176 in the front surface to receive theprotruding pins 62 and 64 of the driven chain links 48. The grooveenables the outside plates 58 of the driven chain links 48 to abutdirectly against the front surface 174 of the support block 172. Thus,while the cylindrical rollers 166 and 168 are pressing the drive chain66 so as to maintain a rigid relationship between abutting links, thesupport block 172 is pressing against the driven chain links 48 tomaintain a rigidity in the driven chain 44 when the first driven section72. The bias means 160 is connected to a housing structure 178 whichencloses the operating structure for the telescoping mast 10.Preferably, bolts 180 and 182 are slidably mounted within apertures 184and 185 in the housing structure 178. The bolts are threadedly receivedwithin the support block 172 and are provided with springs 186 and 188which act against collars 190 and 192 to concurrently press thecylindrical rollers 166 and 168 against the drive chain 66 whilepressing the support block 172 against the driven chain 44. It is withinthe terms of the present invention to change the biasing force on thedrive chain and driven chain by the selection of the spring 186 and 188.Further, although a specific design is presented for concurrentlybiasing both the drive chain and the driven chain, it is within theterms of the present invention to provide some other device to maintainthe drive and driven chain within the first drive and driven sections 70and 72, respectively, in an axis extending in the longitudinal direction148.

Referring to FIGS. 9 and 10, the driven chain 44 has a first drivensection 72 passing through the bias means 160 and a second drivensection 191 being wound onto a drive chain spool 195. A transitiondriver section 193 is disposed between the first driven section 172 andthe second driven section 191. The transition section 193 includes atransition element 194 having a curvilinear surface 196 which slidablycontacts the driven rollers 54 and 56 to enable the driven chain 44 tosmoothly move to the longitudinal direction 148 from a transversedirection 197.

Referring to FIGS. 2 and 11, the details of the telescoping mastsections are illustrated. The bottom mast section 12, as illustrated inFIG. 11, is received within a collar 198. One end of the mast section 12can include a neck section 200 having a groove 202 extending thereaboutfor receiving a set screw 204 for securing the lower half section inplace. Note that the collar 198 can be affixed to the support or housingstructure 178 by any conventional means such as bolts 206. The lowermast section can protrude from the top of the vehicle 11 and be providedwith seal structure 208 and 210 to prevent any moisture from enteringthe inside of the vehicle 11. Affixed to the upper end of the lower mastsection 12 is an inwardly extending flange 30 with a seal 32 to engagethe outer peripheral surface of a mast section 14. Thus, as the mastsection 14 moves with respect to the flange 30, moisture and otherenvironmental contaminants are prevented from collecting between thelower mast section 12 and the middle mast sections 14. In addition, theflange 30 can also be used as a bearing device with respect to the mastsection 14. As illustrated in FIG. 12, the mast sections are nestedtogether.

Internal wiring 310 can be provided within the sections. The wiring canbe connected at one end to the equipment 18 on top of the mast and to apower or signal source in any other desired electrical circuitry in themast support, such as vehicle 11. The wiring 310 can be fed through anaperture in flange 22, not shown. It is, however, within the terms ofthe present invention to run the wiring 310' external to the mast asshown in FIG. 2.

In operation, the drive sprocket 74 is rotated in a clockwise directionto move the first section of the drive chain 66 in the directionindicated by 148. As illustrated in FIG. 13, one end of the drive chain66 is connected to a connector link 76. At the same time, an upper endof the driven chain 44 is also connected to the connector link 76. Acylindrical rod 209 having a curved surface 211 is affixed to the top ofthe connector link 76. The innermost mast section 16 has a plug bottom212 which is affixed to the bottom of the innermost section 16 by anydesired means. A spherical element 214 is fixedly received within theplug and held there by enclosure element 216. The enclosure elementincludes an aperture 218 extending therethrough having a larger apertureopening than the rod 209 so that the surface 210 of the rod 208 can moveand adjust itself and the cylindrical element 214 to accommodate anymisalignment between the rigid drive mechanism 38 and the innermostsection 16. When the innermost section 16 moves to its most extendedposition as shown in FIGS. 2 and 13, an interfacing collar 220 receivedwithin a keyway 222, formed on the innermost mast section 16, abutsagainst the plug 212 and prevents further movement of the innermost mastupward with respect to the surrounding mast section 14. As the innermostmast section continues to move upward, the mast sections attached tocollar 220, i.e. section 14' ''continues to move upward. When section14''' is fully extended, the next outer section, i.e. 14", begins toextend upward. This sequence of events continues until the mast is fullyextended. It can be appreciated that the movement of the rigid driveassembly can be stopped at any time and therefore positioning of themast assembly can be precisely controlled.

As seen in FIG. 4, each of the mast sections includes at least oneaperture 226 through which an observer can view indicia printed on thelinks of either the drive or driven chain to indicate the height towhich the mast has been extended. When the mast sections are in thefully retracted position, an observer can view the indicia on thechains. However, as the mast sections begin to extend upwards, the viewcan be interrupted. Therefore, it is within the terms of the presentinvention to incorporate additional holes in the mast sections, ifdesired, to more precisely determine the height level.

Referring to FIG. 14, there is shown a modification of the firstembodiment of the present invention. The drive chain links 228 areconstructed, as illustrated in FIG. 16, with the inside link 230 havinginside or inner plates 232 and 234 being interconnected by a first plateelement 236. If desired, the elements of the inside link can be formedof a single integral piece of material. The outside link 238 includesoutside plates 240 and 242 and an outside plate element 244 extendingbetween the two outside plates. The plate element 244 includes a groove246. The lower inside apertures 248 are connected to the two outerapertures 250 by means of a stud 252. In the same way, the upper innerapertures 254 are connected to the lower outer apertures 256 by means ofa stud 252. As in the first embodiment, a bushing and roller areprovided on the studs to form a standard roller chain. As with the firstembodiment, the end surface 258 of the first plate 236 abuts against theend surface 260 of the plate 244 so that the groove 246 and surface 258form an aperture 262.

Referring now to the driven chain links 264, two driven inside plates266 and 268 have bushings and rollers 270 therebetween. Outside drivenplates 272 and 274 connect the inside plates and are attached thereto bya pin 276. The outside plate 272 has projecting fingers 278 and 280extending from either end to cooperate with the drive plates 236 and 244in the same manner as with the first embodiment. Note that the finger280 is of a suitable length to abut against the surface 282 of the plate244. The finger 278 includes a groove 284 to be received within theaperture 262.

The operation of the second embodiment is substantially the same as thefirst embodiment. That is, as the driven chain links 264 move up or downin the lateral direction 148, the fingers 278 disposed in the apertures262 simultaneously effect the movement of the driven chain links 264.

A third modification is shown in FIGS. 19 and 20. The driven chain links290 include first and second inside driven plates 292 and 294 and firstand second outside driven plates 296 and 298. The inside and outsidedriven plates are connected together by pins and rollers as in theprevious embodiments. Each of the inside and outside driven plates 294and 298 which are adjacent to the drive chain links 300 include a drivenfinger 302 and 304 which can be punched out of the plates. These fingers302 and 304 are sized to either abut against or be received within theaperture in the drive chain 300 which is substantially the same as thedrive chain 224 described in the second embodiment or the drive chain 66described with regards to the first embodiment.

Both the drive chain 66 and the driven chain 44 can be constructed ofmaterials selected from the group comprising ferrous, non-ferrous,metallic and non-metallic materials.

Although the drive chain has been disclosed with an aperture extendingtherein to receive a finger from the driven chain, it is also within thescope of the present invention to reverse the chains so that the drivechain includes the projecting fingers and the driven chain includes theapertures to receive the projecting fingers.

Although the drive and driven chains are disclosed as being wound ontochain spools, it is within the terms of the present invention to let thechains extend freely in any direction. Moreover, they can be run througha serpentine track or simply increased in length, as desired, by anoperator.

The invention has been described with reference to a preferredembodiment and it is apparent that many modifications may beincorporated into the design and configuration of the telescoping mastassembly discussed herein without departing from the spirit or theessence of the invention. It is my intention to include all suchmodifications and alterations insofar as they come within the scope ofmy invention. It is thus the essence of my invention to provide atelescoping mast assembly which can be readily adapted and configured tobe incorporated in a wide variety of applications.

Having thus defined the invention, the following is claimed:
 1. A driveassembly, comprising:a drive head for movement in a generally fixed,straight line between a first position and a second position; a rigiddrive device for moving said drive head between said first position andsaid second position, said rigid drive device comprising: first andsecond flexible elements; and means integrally connected to said firstand second flexible elements for rigidly connecting said first andsecond flexible elements between the first and second positions wherebythe interconnected flexible elements form the rigid drive device.
 2. Thedrive assembly of claim 1 wherein said first flexible elementcomprises:a driven chain having a plurality of interconnected drivenchain links, said driven chain having a first driven section extendingin the longitudinal direction between the first position and the secondposition; and, a first end of said first driven section being connectedto said drive head.
 3. The drive assembly of claim 2 wherein said secondflexible element comprises:a drive chain having a first drive sectionextending in the longitudinal direction between said first position andsaid second position; and, a first end of said first drive section beingconnected to said drive head.
 4. The drive assembly of claim 3 whereinthe integrally connected means includes latching means interconnectingthe first drive section and the first driven section to form the rigiddrive device.
 5. The drive assembly of claim 4 wherein said first drivesection and said first driven section are disposed adjacent to eachother.
 6. The drive assembly of claim 5 wherein:said drive chain isconstructed of a plurality of interconnected drive links having saidlatching means connected thereto; and, said driven chain is constructedof a plurality of interconnected driven links having said latching meansaffixed thereto whereby the driven links are interconnected to the drivelinks in the first drive and first driven sections so that said firstdriven section can be driven by the movement of said first drivesection.
 7. The drive assembly of claim 6 wherein each of said drivelinks has plate element means affixed thereto, said plate element meansbeing disposed in said first drive section in abutting relationship torigidly affix adjacent drive links to each other.
 8. The drive assemblyof claim 7 wherein said plate element means, comprises:a plurality offirst plate elements constructed of a substantially rectangular firstplate having a substantially flat, upper edge surface with a plate slotformed therein and an opposing substantially flat lower edge surface; aplurality of second plate elements constructed of a substantiallyrectangular second plate having substantially flat upper and lower edgesurfaces; and, said first and second plate elements being alternatelydisposed between each other in the first drive section whereby the flatupper edge surface of the second plate element abuts the substantiallyflat lower edge surface of the first plate element and the substantiallyflat upper edge surface of the first plate element abuts thesubstantially flat lower edge surface of the second plate element toprovide an aperture therebetween.
 9. The drive assembly of claim 8wherein each of said driven links has projecting element means attachedthereto for interconnecting the driven links to the drive links in thefirst drive section.
 10. The drive assembly of claim 9 wherein saidprojecting element means comprises:a plurality of first projectingelements having a substantially flat, first end with a rectangularcross-section, each of said first projecting elements being affixed to adriven link at a second and oppositely disposed end from said first endand extending transversely outwardly from the longitudinally disposedfirst driven section; a plurality of second projecting elements having asubstantially rectangular cross-section with a substantially flat, uppersurface and a substantially flat, lower surface, said flat lower surfacehaving a projecting element slot formed therein; and, said first andsecond projecting elements being affixed to alternate, adjacent drivenlinks whereby the substantially flat end of the first projectingelements abut against the first plate elements to maintain the distancebetween the drive and driven sections and the second projecting elementsare received within the plate aperture with the projecting element slotbeing disposed to receive the plate slot formed in the upper edgesurface of the first plate.
 11. The drive assembly of claim 10 whereinsaid projecting element means are flexibly mounted to said driven linksto prevent interference due to misalignment of the projecting elementmeans and the plate element means.
 12. The drive assembly of claim 10wherein each of said driven link means includes:spaced inner drivenlinks constructed of two parallel inner driven plates separated by twodriven rollers; and, outer driven links including two parallel drivenlinks constructed of two parallel outer driven plates connectingadjacent inner driven links.
 13. The drive assembly of claim 12 whereina first projecting element is affixed at the second end to the innerdriven plate; and,a second projecting element is affixed at the secondend to the outer driven plate.
 14. The drive assembly of claim 12wherein:a first projecting element is affixed at the second end to afirst end of the outer driven plate; and, a second projecting element isaffixed at the second end to a second end of the outer driven plate. 15.The drive assembly of claim 14, wherein:each of said drive link meansincludes a plurality of spaced inner drive links having twosubstantially parallel inner drive plates separated by two driverollers; a plurality of outer drive links including two parallel outerdrive plates connecting adjacent inner drive links; and wherein saiddrive link means includes a first plate affixed to the inner driveplates and a second plate affixed to the outer drive plates; and whereinsaid first plate is integral with said inner drive plates and saidsecond plate is integral with said outer drive plates.
 16. The driveassembly of claim 13 wherein:said first projecting element is anintegral section of said inner driven plate and is punched out of saidinner driven plate; and said second projecting element is an integralsection of said outer driven plate and is punched out said outer plate.17. The drive assembly of claim 8 wherein:each of said drive link meansincludes a plurality of spaced inner drive links having twosubstantially parallel inner drive plates separated by two driverollers; and, a plurality of outer drive links including two parallelouter drive plates connecting adjacent inner drive links.
 18. The driveassembly of claim 17 wherein said drive link means includes a firstplate affixed to the inner drive plates and a second plate affixed tothe outer drive plates.
 19. The drive assembly of claim 18 wherein thefirst and second plates extend outwardly from the inner and outer driveplates.
 20. The drive assembly of claim 18, wherein said first plate isintegral with said inner drive plates and said second plate is integralwith said outer drive plates.
 21. The drive assembly in claim 4 whereinsaid drive chain includes a second drive section being connected to saidfirst drive section and extending transversely to said first drivesection.
 22. The drive assembly of claim 20 wherein said drive chainincludes a second driven section connected to said first driven sectionand extending transversely to said first driven section.
 23. The driveassembly of claim 4 further including a drive sprocket disposed at theintersection of the first ant second drive sections for engaging thedrive links to extend and retract the first drive section.
 24. The driveassembly of claim 23 further including power drive means for selectivelyrotating said drive sprocket.
 25. The drive assembly of claim 23 whereinsaid drive sprocket has a substantially cylindrical peripheral surfaceand includes a plurality of sprocket grooves having substantially equalspacing about the peripheral surface for engaging said drive chain. 26.The drive assembly of claim 25 wherein the cylindrical peripheralsurface of said drive sprocket presses said plate elements into abutmentwith each other to rigidly affix adjacent drive links, and saidcylindrical peripheral surface further presses said plate elementstowards the driven chain in a transverse direction to the longitudinaldirection of the first driven section.
 27. The drive assembly of claim26 further including biasing means for pressing said plate elementstoward the drive sprocket whereby a rigid interconnection between thedrive plates in the first drive section is maintained.
 28. The driveassembly of claim 27 wherein said biasing means comprises first andsecond cylindrical rollers spaced apart to receive said first drivesection of interconnected driven links.
 29. The drive assembly of claim28 wherein:said first and second cylindrical rollers are interconnectedby a shaft; and, spring means interconnected with said shaft to bias thecylindrical rollers toward said drive sprocket.
 30. The drive assemblyof claim 29 wherein said biasing means further includes a support blockdisposed between said cylindrical rollers whereby said cylindricalrollers abut against said drive chain while said support blocksimultaneously abuts against said driven chain to maintain the rigidityof both the first drive section and the first driven section.
 31. Thedrive assembly of claim 30 wherein said biasing means furtherincludes:said cylindrical roller being connected to said support block;and, said spring means simultaneously biasing said support block andsaid cylindrical rollers against said first driven section and saidfirst drive sections.
 32. The drive assembly of claim 1 furtherincluding a mast comprising a plurality of interconnected mast sectionsnested within each other for movement between said first positionwherein the mast section are fully retracted and said second positionwhere the mast sections are fully extended.
 33. The drive assembly ofclaim 32 further including:indicia means for indicating the preciseposition of the mast, said indicia being marked on said rigid drivedevice; and, aperture means in each of said plurality of interconnectedmast sections for viewing the indicia.
 34. The drive assembly of claim32 further including connector means for interconnecting the drive headto the innermost movable mast section to accommodate said movement ofthe mast sections.
 35. A drive assembly for moving a member along alinear path between first and second positions comprising driving anddriven link chain means each having a plurality of link meansinterconnected for pivotal movement about corresponding link axes, thelink axes of said driving link chain means being perpendicular to thelink axes of said driven link chain means along said path, and said linkmeans of said driving and driven link chain means includinginterengaging means for said driving link chain means to displace saiddriven link chain means along said path and for restraining pivotalmovement of said link means about said corresponding link axes.
 36. Thedrive assembly according to claim 35, wherein said interengaging meansincludes means on one of said driving and driven link chain meansproviding openings transverse to said path and finger means on the otherof said driving and said driven link chain means received in saidopenings.
 37. The drive assembly according to claim 36, wherein saidfinger means include means interengaging with said means on said one ofsaid driving and driven link chain means to restrain displacement ofsaid finger means from said openings transverse to said path.
 38. Thedrive assembly according to claim 36, wherein adjacent link means ofsaid one of said driving and driven link chain means includes platemeans having opposed edge means, said openings being provided betweensaid opposed edge means.
 39. The drive assembly according to claim 38,wherein said finger means include means interengaging with said platemeans to restrain displacement of said finger means from said openingstransverse to said path.
 40. The drive assembly according to claim 39,wherein said openings are provided by a notch in one of said opposededge means and the portion of the other of said opposed edge meansfacing said notch.
 41. The drive assembly according to claim 40, whereinsaid means of said finger means interengaging with said plate meansincludes notch means in said finger means.
 42. The drive assemblyaccording to claim 38, wherein said plate means are integral with saidlink means of said driving link means.
 43. The drive assembly accordingto claim 38, wherein said plate means are mounted on said link means ofsaid driving link chain means.
 44. The drive assembly according to claim36, wherein said finger means are on said driven link chain means andintegral with said link means thereof.
 45. The drive assembly accordingto claim 36, wherein said finger means are on said driven link chainmeans and mounted on said link means thereof.
 46. A drive assembly formoving an object along a linear path comprising first and second linkchain means each having a plurality of link means interconnected forpivotal movement about corresponding link axes, the link axes of saidfirst link chain means being at an angle to the link axes of said secondlink chain means along said path, and said link means of said first andsecond link chain means including means interengaging said first andsecond link chain means along said path to restrain pivotal movement ofsaid link means about said corresponding axes.